Java/JRuby Developers, Say Open 'Sesame' to the Semantic Web

he core concept of the semantic web is integrating and using data from different sources. Using semantic web technologies such as RDF/RDFS and the SPARQL query language to integrate and use data from disparate sources has some advantages over using a standard relational database. The Resource Description Framework (RDF) uses predicates to define relationships between data objects, and RDF Schema (RDFS), which is written in RDF, offers a modeling language for knowledge representation and ontology development. (See Sidebar 1. Why RDF/RDFS for the Semantic Web?) Used together, these technologies enable you to use information from disparate sources in different formats/schemas without having to convert the data to a "standard format"—as you would with a relational database.

This article introduces Java developers to semantic web application development using Java and JRuby. It demonstrates how to employ the semantic web's functionality through an application example that processes news articles to identify and store (in an RDF repository) industry terms and the names of people and places. The example uses the Sesame libraries for RDF storage, RDFS inferencing, and running SPARQL queries, and the downloadable source code provides a simple wrapper API for Sesame and some examples of queries against sample RDF data.